If you have something like Free Trial Class or Free Fitness Assessment, here is the recommended way to set that up.
Create New Plan
Select 'Punchcard' as the type
Its good to make it expire after a week in case they don't use it, it will clear it off active plan lists. Also creates some urgency so they use it.
Set total Check-ins to '1'
Set Landing page redirect to book class
Set 'Are People Who Buy This A Member?' to NO.
Set 'Trial Membership' to YES (this will put them in your lead section)
Its better to have this as a Punchcard rather than Non-recurring as it will automatically switch to 'completed' status once they check-in against it and use it.
This is a better method to get prospects in the door than a general contact us type form. Here you are giving the prospect something, 'a free session', which they are far more likely to come in and redeem. Use the Landing Page link this creates as the primary Call to Action link you are promoting on your website.